Vacuum tube



Aug. 8, 1933. c. J. KAYKQ 1,921,619

VACUUM TUBE Fild May 2l, 1928 Patented` Aug. 8, 1933 UNITED STATES PATENT oF1=1cE VACUUM TUBE Charles J. Kayko, Jackson, Mich., assigner, by

mesne assignments, to The Sparks-Withington Company, Jackson, Mich., a Corporation of Ohio Application May' 21, 192s. serial No. 279,595

4 Claims.

Another object is to provide a type of con-v struction Whichis rugged and will not go out of shape easily.

Another object is so to choose the material of which the heater is made that electrons Will be emitted from it with diiculty, thereby minimizing hum when alternating current flows through the heater.

Another of the objects of my invention is to shield the parts of the tube involved in the space discharge phenomenon from those associated with the heating of the cathode whereby hum may be completely eliminated.

How` lI accomplish these results is clearly set forth in the following specification:

Figure 1 is a sectionalized view of my tube in which --1- is a metal helix secured to the conducting members 6.6 by Welds shown at 5.5.

2 is a rod of any suitable material covered v with emitter material such as an alkalineearth oxide or oxides. The tip of part -2- (the emitter and cathode) projects beyond the helical heater -1. Disposed` above said heating coil is a Washer-like shield -3- suitably supported by wire I3- welded to bead l0- and by lead -14 and through the central hole of the shield theVV tip of the emitter -2- projects.

Above this shield suitably supported a screengrid -4`- is Vplaced which for stiffness may also be ,welded to a wire V12- .projecting from an insulating bead 10 melted on the plate support -11-- and the grid may be welded to vthe lead -15.

Above the grid, welded to the support 11 is a plate -16- as for instance in the form of a round disk of any suitable metal. Further, the plate may be welded to thelead -17-.

The operation of this very simple tube is as follows: `Alternating current is fed into the heating helix 1-. Since the heater coil is not connected to any of the so-called radio parts of the tube, electrons emitted from this coil will be of a random nature, but usually unless thev current density and temperature of the helix is low, Will be emitted in suiicient` strength to cause a serious hum. If, however, a small potential diierence is applied between the heater filament and the shield -3- whatever electrons may be shot off from the fllament will pass to the shield, and the main flow of electrons from the tip of the cathode to theplate will not bey interfered with. Suchv a tube is silent in operation.Y

It will thus berseen that I'have produced a Verysiinpe device which makes A. C; operation. of radio tubes practical. I have eliminated, too, many aggravating points in the manufacture of such tubes, such as the de-gassing of porcelain insulatorsV etc. The small amount of material in. the tube makes pumping a simple process. I have illustrated the actual tubes I have made. It is, of course, obvious to those skilled inthe art, that the geometrical arrangement of the v parts may be Widely Varied and :yet produce precisely-the same result.

I claim: 1

1. A vacuum tube comprisingY a plate, a grid, a heating` element, a cathode Within said heating element and adapted to be heated' by direct radiation therefrom, a shield electrode interposed between the heater and the grid of the tube said grid and said Yplate, being positioned,

on the opposite side of lsaid shield from said,

heating element. 1 Y

2. In a vacuum tube, a helical heater, a cathode co-axially disposed.A Withinsaid heater but out of velectrical contact therewith, a grid and a plate element disposed in operative relation abovesaid heater, saidcathode having a portion extending beyond said heater in Va direction toward said'grid and plate elements, and a metallic shield element disposed between said heater and said grid and said plate elements for preventing random electrons from saidheater from interfering with the plate current flow.

3. In a vacuum. tube, a heater element, a cath-l ode covered with a coating, of high. emission material disposed within said heater element and adapted to be heated by direct radiation therefrom, a grid, a plate, a metallic shield element having an orifice disposed between said heater element and said grid, said cathode having a portion projecting through the orifice inl said shield element.

4. In a VacuumA tube, a `heating element, a cathode surrounded in part by said heating element, but out of electrical contact therewith and adapted to be heated by direct radiation from said element, a grid, a plateand a metallic shield interposed between the heater and said grid for preventing random` electrons emitted from the heater from interfering with the plate current flow. l

. CHAS. J. KAYKOl 

